Various waxes are available to the expert for the production of cosmetic and/or pharmaceutical formulations, acting both as consistency factors—particularly by building up lamellar structures—and as co-emulsifiers.
In formulations produced by the PIT process (PIT=phase inversion temperature), mono-/di-/triglyceride mixtures are commonly used as co-emulsifiers. The mono-/di-/triglyceride ratio and the emulsifier/co-emulsifier ratio have to be carefully adapted for this particular application. In DE 100 25 671 A1 for example, it is emphasized that the monoglyceride content must not fall below a certain value in order to obtain particularly fine-particle emulsions which are stable in storage and do not gel, even under temperature stress. This means that narrow limits have to be observed for the production of emulsifier compositions for PIT emulsions based on glycerides. However, this is not without production-related problems. Even in long-term storage, the ratio of the mono-, di- and triglycerides to one another can change.
Formulations produced by the PIT process are generally distinguished by a particularly fine droplet distribution and good stability. However, where mono- and diesters of glycerol are used as co-emulsifiers, inter- and intramolecular migration can occur. In this event, a 1-acyl glyceride mixture, for example, isomerizes into a mixture of 1- and 2-acyl glycerides or disproportionation to glycerol and the diglycerides 1,2-diacyl and 1,3-diacyl glyceride and the corresponding triglyceride occurs (cf. J. D. Brandner, R. L. Birkmeier, J. Am. Oil Chem. Soc. 1960, 37, 390-396; J. D. Brandner, R. L. Birkmeier, J. Am. Oil Chem. Soc. 1964, 41, 367-370). The scale of these isomerization and disproportionation reactions is time- and temperature-dependent and, in addition, can also depend on the catalyst used for the production of the glycerides. The phenomenon of acyl migration in glycerides complicates their selective synthesis and also influences their applicational properties. Emulsifier mixtures which contain partial glycerides as co-emulsifiers and which are used for the production of PIT emulsions often show hugely varying properties from batch to batch, so that reproducibility of the final formulation cannot always be guaranteed.
There remains a need to provide emulsifier compositions which can be used in a broad mixing ratio, are suitable in particular for the production of PIT emulsions and are not attended by the problems observed with partial glycerides as so-emulsifiers. There also remains a need to provide emulsifier compositions which are suitable for the production of PIT and microemulsions having a particle size of 1000 nm or smaller.